1. Field of the Invention
The present invention relates to an image formation device for forming an image after temporarily storing the image in an optical image memory and then reading it.
2. Description of the Prior Art
The U.S. Pat. No. 3,796,999 discloses a display in which laser beam is selectively directed to a liquid crystal cell to display an image on the liquid crystal. The theory of the display is that the heat of the laser beam is utilized to partially change the liquid crystal in phase and an image is formed corresponding to a pattern with which the laser beam is directed. The liquid crystal employed herein is, for example, a smectic liquid crystal.
Japanese Unexamined Patent Publication No. 20773/1989 discloses a device forming an image with the above-mentioned thermal writing type liquid crystal cell. Transmitted or reflected light of the liquid crystal cell is directed to photosensitive material to form a latent image on the photosensitive material, and an image is formed based upon the latent image. Further, a full color image can be also formed by using three liquid crystal cells having primary color R(red), G(green) and B(blue) images written to compose the three images.
In the photosensitive material as previously mentioned, light is irradiated in some part but not in other part to change the state, and thus a latent image is formed. From the part of the photosensitive material which is not irradiated by light, color coupler is discharged upon a pressure development.
When a laten image is formed in the photosensitive material, the photosensitive material is exposed only in areas storing images of the liquid crystal cells. Thus, the photosensitive material has areas unexposed around the exposed areas. The color coupler in the unexposed areas is discharged upon the pressure development to dirty a pressure development unit. To solve it, the unexposed areas are forcibly exposed by a light source other than the light source used for exposure before the pressure development; in this way, however, an extra light source is required; therefore, the device should be larger in size and higher in manufacturing cost.